1. Field
This patent document relates to a semiconductor design technology and, more particularly, to a dual in-line memory module (DIMM) capable of performing a repair operation.
2. Description of the Related Art
Semiconductor memory devices are fabricated in the form required by a system to which they are applied, in order to realize their large capacity and high performance. For example, for a system such as a personal computer (PC), a plurality of memory devices are integrated on one printed circuit board (PCB), and provided in the form of a module. The module is mounted in the system through slots.
Among modules of semiconductor memory devices, one of the most common modules is a dual in-line memory module (DIMM).
The DIMM may include a plurality of dynamic random access memory (DRAM) chips and registers mounted therein. When a defect occurs in any one of a large number of micro-cells forming a DRAM chip, the DRAM chip may not properly perform its function. In this case, a redundancy method may be employed, which replaces a defective cell with a redundant memory cell installed in the DRAM chip, thereby increasing the yield. According to the redundancy method, when memory cells are checked as defective cells, they are replaced with prepared redundancy cells on a row/column basis. Thus, the DRAM chip may not be discarded but continued to be used.
However, in the case of a DIMM including a plurality of DRAM chips, one or more DRAM chips are to be driven according to the same command and address. That is, banks within the DRAM chips may be mapped to each other, and rows or columns of cells of the mapped banks may be accessed according to the same command and address. When defective cells included in the respective DRAM chips are positioned at different rows or columns, the DRAM chips which are driven according to the same command and address cannot use all the rows or columns even though the rows or columns correspond to defective cells of the other chips. Thus, the yield of the entire DIMM is degraded.
Thus, a scheme for a more efficient repair operation of a DIMM is needed.